EXCAVATING MACHINERY USED IN LAND DRAINAGE. 59 
level the waste bank of the old ditch sufficiently for the machine to 
pass over it. 
SUMMARY. 
Power machinery is available that will construct outlet drainage 
ditches of all sizes and under all conditions of soil and water cheaper 
than can be accomplished by any other method. The floating dipper 
dredge is more widely used in drainage work than is any other type 
of excavating machine. No other excavator will equa] it in con- 
structing ditches from 100 to 1,200 square feet in cross-section 
through wet, timbered land. It is the most efficient machine to use 
-where numerous stumps will be encountered. Owing to its limited 
reach, it is not generally applicable to levee construction. Dipper 
dredges range in capacity from three-fourths cubic yard to 5 cubic 
yards; the sizes most commonly used vary from 1 to 3 cubic yards. 
The clam-shell and orange-peel dredges are not widely used in 
ditch construction except in soils such as the muck of southern 
Louisiana and California, which are free from stumps and logs. If 
equipped with a long boom such a dredge can be economically used 
to construct levees where there is water to float the machine. 
The drag-line scraper excavator is well suited to the construction of 
ditches and levees, especially those of large cross-section, where the 
ground is sufficiently stable to support the machine. It is also 
adapted to clean-out work and to ditch enlargement. It is a flexible 
machine, adapted to a wide range of working conditions. 
The various forms of dry-land machines find extensive use in drain- 
age. The walking dry-land dipper dredge is especially useful in 
drainage districts where ditch cross-sections are small and there are 
many short, detached ditches. The grab-bucket dredges of the dry- 
land class are suitable where sufficient water can not be had to float 
a dredge. 
The wheel type of excavator is applicable to open flat land where 
the soil is neither too hard nor too wet. The ditches cut by these 
machines have a more uniform cross-section than can be cut by other 
excavators. 
The hydraulic dredge is not suited to ordinary drainage ditch con- 
struction. Where water is available it is applicable to the construc- 
tion of very large channels and also for building levees where the 
material is such as will not remain Jong in suspension. 
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